Various conductive pastes for die bonding containing silver particles, and various die bonding methods for semiconductor devices using the conductive pastes have been hitherto suggested.
For example, a paste-like silver composition for adhesion of metal-based adherends, which is sintered by heating and is thereby converted to solid silver having excellent strength, electrical conductivity and thermal conductivity, has been suggested (see Patent Document 1).
More specifically, disclosed is a paste-like silver composition for bonding between metal-based adherends, which includes (A) spherical silver particles produced by a reducing method, having an average particle size of 0.1 to 6 μm and a carbon content of 0.50% by weight or less; and (B) a volatile dispersing medium having a boiling point of 70° C. to 250° C. and selected from water, volatile monohydric alcohols, volatile aliphatic hydrocarbons, volatile ketones, volatile lower aliphatic carboxylic acid esters, and volatile silicone oils, characterized in that when the paste-like composition is heated to a temperature of from 100° C. to 250° C., the volatile dispersing medium is volatilized, and thereby the spherical silver particles are sintered and are converted to solid silver having a volume resistivity of 1×10−4 Ω·cm or less and a thermal conductivity of 5 W/m·K or more.
Furthermore, there has been suggested a method of forming a hot sintered product with fewer cracks by controlling the sinterability of particles, and thereby strongly bonding metal-based adherends with each other (see Patent Document 2).
More specifically, disclosed is a method for bonding metallic members, characterized by inserting a paste-like metal particle composition including (A) hot sinterable metal particles having an average particle size of above 0.1 μm and 50 μm or less, and (B) a volatile dispersing medium, between plural metallic members, volatilizing the volatile dispersing medium (B) in the paste-like metal particle composition in an amount of 10% by weight or more but below 100% by weight by heating in an inert gas at a temperature of from 40° C. to 200° C., subsequently volatilizing the volatile dispersing medium (B) remaining in the paste-like metal particle composition by heating in an oxidizing gas or a reducing gas at a temperature of from 70° C. to 400° C., thus sintering the hot sinterable metal particles (A), and thereby bonding the plural metallic members.
Furthermore, there has been suggested a paste-like silver particle composition in which silver particles are easily sintered when the composition is heated while eliminating the influence of long-chain fatty acids and the like that cover the surface of hot sinterable metal particles, and are thereby converted to solid silver having excellent strength, electrical conductivity and thermal conductivity (see Patent Document 3).
More specifically, disclosed is a paste-like silver particle composition including (A) silver particles having their surface covered with long- and medium-chain fatty acids (b1) or derivatives (b2) of long- and medium-chain fatty acids (b1), and (B) a volatile dispersing medium, in which the volatile dispersing medium is volatilized by heating and thereby the silver particles are sintered, characterized in that the long- and medium-chain fatty acids (b1) or the derivatives (b2) of long- and medium-chain fatty acids (b1) that cover the silver particle surface, are products obtained by replacing the long-chain fatty acids (a1) or derivatives (a2) of long-chain fatty acids (a1) that have been previously covering the silver particle surface, with long- and medium-chain fatty acids (b1) or derivatives (b2) of long- and medium-chain fatty acids (b1) that are shorter than the long-chain fatty acids (a1).
Furthermore, there have been suggested flat silver particles that have enhanced orientation properties when used to form a conductor film, so that a low resistant conductor film may be obtained therefrom (see Patent Document 4).
More specifically, disclosed are flat silver particles characterized in that the ratio P200/P111 of the peak P200 of a (200) plane with respect to the peak P111 of a (111) plane, which is obtained by an XRD analysis, is 0.3 or less.